The present invention relates to a method and apparatus for performing automatic callback. The invention can be implemented in an Advanced Intelligent Network (AIN) environment. The system is particularly useful in the management of dial-up connections between subscribers and an Internet Services Provider (ISP).
ACB: Automatic Call Back;
(A)IN: (Advanced) Intelligent Network;
BCM: Basic Call Model
DN: Dialled Number;
DP: Detection Point;
DTMF: Dual-Tone Multifrequency;
EDP: Event Detection Point;
IP: Intelligent Peripheral;
ISP: Internet Services Provider;
PC: Personal Computer;
PIC: Point-in-Call;
SCP; Service Control Point;
SS7: Signalling System 7;
SSP: Service Switching Point;
TCAP: Transaction Capability Application Part;
TDP: Trigger Detection Point;
Currently, when a user wants access to the Internet, he/she dials up, through the modem connected to the Personal Computer (PC), the ISP""s telephone number for connection to one of the modems from its pool of modems. Sometimes, none of the ISP modems are available. In such cases, the user will receive an advisory message or a busy signal and, depending on his software setup, his modem will redial after a certain period of time until it successfully connects to the ISP.
A problem with this approach is that if one of the ISP""s modems becomes available in between the successive dial-ups, someone else may obtain the line. The result is that the user waits unnecessarily to obtain a connection to his ISP. Furthermore, this method consumes network resources unnecessarily thereby incurring costs to the telephone operating company.
A possible solution is to adjust the software to reduce the time between dial-ups thereby increasing the likelihood of connecting to the first available modem. An obvious disadvantage of this method is that it keeps the line and network resources unnecessarily busy for long periods of time, especially if none of the ISP""s modems become available for a while. This solution also incurs unnecessary costs to the telephone operating company. In addition, a high rate of re-dial may trigger a protection mechanism in the telephone network designed to limit the velocity of call attempts. In such situation, the telephone network may become non-responsive to call attempts.
Thus, there exists a need in the industry to provide a system to manage the utilisation of a pool of modems through which multiple users can establish dial-up connections.
In summary, the invention provides an apparatus for use in a telecommunication network to provide automatic call-back (ACB) to a modem attempting to establish a data exchange session with a called party. The apparatus has an input to receive an input control signal from the telecommunication network signalling a busy line condition event at the called party. When the busy line condition ceases, as may be determined by another control signal received from the telecommunication network, the apparatus issues an output control signal directing the telecommunication network to notify the calling modem to re-try establishing the data exchange session with the called party.
In a specific example of the present invention the ACB feature is implemented on an SCP of the telecommunications network. The SCP is the AIN entity that provides database supported subscriber services.
Under this preferred embodiment of the invention, the telecommunications network notifies the SCP (typically the message originates from the SSP servicing the called modem) once a line to one of the ISP modems becomes available. The SCP will send a message to the network (typically the message is sent to the SSP serving the calling modem) to notify the calling modem that the line is now free. At the same time the SCP directs the SSP servicing the calling modem to observe the line condition. When the line goes off-hook, the SSP generates dial tone so the modem can re-dial
More specifically, the procedure for dial tone generation includes the following steps The first step is the detection of the off-hook condition. This detection is performed by the SSP that observes the state of the telephone line of the calling party. When the off-hook condition is detected, the SSP issues a message to the SCP to advise the SCP of this event. The SCP sends dial tone establishment instructions to the SSP. The calling modem then dials the digits and waits for the carrier.
The SCP may be provided with a database to store entries related to unsuccessful communication attempts. Each entry includes a time stamp allowing to age the entry. When the line becomes free, the SCP searches the database and notifies the calling party that corresponds to the oldest entry, i.e., the person that has been waiting the longest. Other possible selection strategies may also be considered and age is only one of them.